////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <iostream>
#include <fstream>

#include "base-text-renderer.h"
#include "builtin-defun-decls.h"
#include "dim-vector.h"
#include "error.h"
#include "file-ops.h"
#include "interpreter.h"
#include "interpreter-private.h"
#include "oct-env.h"
#include "oct-process.h"

namespace octave
{
  // FIXME: get rid of this global variable
  // Store both the generated pixmap and the svg image
  typedef std::pair<uint8NDArray /*pixels*/, std::string /*svg*/> latex_data;
  std::unordered_map<std::string, latex_data> latex_cache;

  std::string
  quote_string (std::string str)
  {
    return ('"' + str + '"');
  }

  class
  OCTINTERP_API
  latex_renderer : public base_text_renderer
 {

  public:

    latex_renderer (void)
      : m_fontsize (10.0), m_fontname ("cmr"), m_tmp_dir (),
        m_color (dim_vector (1, 3), 0), m_latex_binary ("latex"),
        m_dvipng_binary ("dvipng"), m_dvisvg_binary ("dvisvgm"),
        m_debug (false), m_testing (true)
      {
        std::string bin = sys::env::getenv ("OCTAVE_LATEX_BINARY");
        if (! bin.empty ())
          m_latex_binary = quote_string (bin);

        bin = sys::env::getenv ("OCTAVE_DVIPNG_BINARY");
        if (! bin.empty ())
          m_dvipng_binary = quote_string (bin);

        bin = sys::env::getenv ("OCTAVE_DVISVG_BINARY");
        if (! bin.empty ())
          m_dvisvg_binary = quote_string (bin);

        m_debug = ! sys::env::getenv ("OCTAVE_LATEX_DEBUG_FLAG").empty ();
      }

    ~latex_renderer (void)
      {
        if (! m_tmp_dir.empty () && ! m_debug)
          sys::recursive_rmdir (m_tmp_dir);
      }

    void set_font (const std::string& /*name*/, const std::string& /*weight*/,
                   const std::string& /*angle*/, double size)
    {
      m_fontsize = size;
    }

    void set_color (const Matrix& c)
    {
      if (c.numel () == 3)
        {
          m_color(0) = static_cast<uint8_t> (c (0) * 255);
          m_color(1) = static_cast<uint8_t> (c (1) * 255);
          m_color(2) = static_cast<uint8_t> (c (2) * 255);
        }
    }

    Matrix get_extent (text_element* /*elt*/, double /*rotation*/)
    {
      return Matrix (1, 2, 0.0);
    }

    Matrix get_extent (const std::string& txt, double rotation,
                       const caseless_str& interpreter)
    {
      Matrix bbox;
      uint8NDArray pixels;
      text_to_pixels (txt, pixels, bbox, 0, 0, rotation, interpreter, false);
      return bbox.extract_n (0, 2, 1, 2);
    }

    void text_to_strlist (const std::string& txt,
                          std::list<text_renderer::string>& lst,
                          Matrix& bbox, int halign, int valign, double rotation,
                          const caseless_str& interp)
    {
      uint8NDArray pixels;
      text_to_pixels (txt, pixels, bbox, halign, valign, rotation,
                      interp, false);

      text_renderer::font fnt;
      text_renderer::string str ("", fnt, 0.0, 0.0);
      str.set_color (m_color);
      str.set_svg_element (latex_cache[key (txt, halign)].second);
      lst.push_back (str);
    }

    void text_to_pixels (const std::string& txt, uint8NDArray& pxls,
                         Matrix& bbox, int halign, int valign, double rotation,
                         const caseless_str& interpreter,
                         bool handle_rotation);

    void set_anti_aliasing (bool /*val*/) { }

    octave_map get_system_fonts (void) { return octave_map (); }

    bool ok (void);

  private:

    std::string key (const std::string& txt, int halign)
    {
      return (txt + ":"
              + std::to_string (m_fontsize) + ":"
              + std::to_string (halign) + ":"
              + std::to_string (m_color(0)) + ":"
              + std::to_string (m_color(1)) + ":"
              + std::to_string (m_color(2)));
    }

    void warn_helper (std::string caller, std::string txt,std::string cmd,
                      process_execution_result result);

    uint8NDArray render (const std::string& txt, int halign = 0);

    bool read_image (const std::string& png_file, uint8NDArray& data) const;

    std::string write_tex_file (const std::string& txt, int halign);

  private:
    double m_fontsize;
    std::string m_fontname;
    std::string m_tmp_dir;
    uint8NDArray m_color;
    std::string m_latex_binary;
    std::string m_dvipng_binary;
    std::string m_dvisvg_binary;
    bool m_debug;
    bool m_testing;

  };

  bool
  latex_renderer::ok (void)
  {
    // Only run the test once in a session
    static bool tested = false;

    static bool isok = false;

    if (! tested)
      {
        tested = true;

        // For testing, render a questoin mark
        uint8NDArray pixels = render ("?");

        if (! pixels.isempty ())
          isok = true;
        else
          warning_with_id ("Octave:LaTeX:internal-error",
                           "latex_renderer: a run-time test failed and the 'latex' interpreter has been disabled.");
      }

    m_testing = false;

    return isok;
  }

  std::string
  latex_renderer::write_tex_file (const std::string& txt, int halign)
  {
    if (m_tmp_dir.empty ())
      {
        //Create the temporary directory
        m_tmp_dir = sys::tempnam ("", "latex");

        if (sys::mkdir (m_tmp_dir, 0700) != 0)
          {
            warning_with_id ("Octave:LaTeX:internal-error",
                             "latex_renderer: unable to create temp directory");
            return std::string ();
          }
      }

    std::string base_file_name
      = sys::file_ops::concat (m_tmp_dir, "default");

    // Duplicate \n characters and align multi-line strings based on
    // horizontalalignment
    std::string latex_txt (txt);
    std::size_t pos = 0;

    while (true)
      {
        pos =  txt.find_first_of ("\n", pos);

        if (pos == std::string::npos)
          break;

        latex_txt.replace (pos, 1, "\n\n");

        pos += 1;
      }

    std::string env ("flushleft");
    if (halign == 1)
      env = "center";
    else if (halign == 2)
      env = "flushright";

    latex_txt = std::string ("\\begin{" ) + env + "}\n"
      + latex_txt + "\n"
      + "\\end{" + env + "}\n";

    // Write to temporary .tex file
    std::ofstream file;
    file.open (base_file_name + ".tex");
    file << "\\documentclass[10pt, varwidth]{standalone}\n"
         << "\\usepackage{amsmath}\n"
         << "\\usepackage[utf8]{inputenc}\n"
         << "\\begin{document}\n"
         << latex_txt << "\n"
         << "\\end{document}";
    file.close ();

    return base_file_name;
  }

  bool
  latex_renderer::read_image (const std::string& png_file,
                              uint8NDArray& data) const
  {
    uint8NDArray alpha;
    uint8NDArray rgb;
    int height;
    int width;

    try
      {
        // First get the image size to build the argument to __magick_read__
        octave_value_list retval = F__magick_ping__ (ovl (png_file), 1);

        octave_scalar_map info
          = retval(0).xscalar_map_value ("latex_renderer::read_image: "
                                         "Wrong type for info");
        height = info.getfield ("rows").int_value ();
        width = info.getfield ("columns").int_value ();
        Cell region (dim_vector(1,2));
        region(0) = range<double> (1.0, height);
        region(1) = range<double> (1.0, width);
        info.setfield ("region", region);
        info.setfield ("index", octave_value (1));

        // Retrieve the alpha map
        retval = F__magick_read__ (ovl (png_file, info), 3);

        alpha = retval(2).xuint8_array_value ("latex_renderer::read_image: "
                                              "Wrong type for alpha");
      }
    catch (const execution_exception& ee)
      {
        warning_with_id ("Octave:LaTeX:internal-error",
                         "latex_renderer:: failed to read png data. %s",
                         ee.message ().c_str ());

        interpreter& interp
          = __get_interpreter__ ("latex_renderer::read_image");

        interp.recover_from_exception ();

        return false;
      }

    data = uint8NDArray (dim_vector (4, width, height),
                             static_cast<uint8_t> (0));

    for (int i = 0; i < height; i++)
      {
        for (int j = 0; j < width; j++)
          {
            data(0, j, i) = m_color(0);
            data(1, j, i) = m_color(1);
            data(2, j, i) = m_color(2);
            data(3, j, i) = alpha(height-i-1,j);
          }
      }

    return true;
  }

  void
  latex_renderer::warn_helper (std::string caller, std::string txt,
                               std::string cmd, process_execution_result result)
  {
    if (m_testing && ! m_debug)
      return;

    if (! m_debug)
      warning_with_id ("Octave:LaTeX:internal-error",
                       "latex_renderer: unable to compile \"%s\"",
                       txt.c_str ());
    else
      warning_with_id ("Octave:LaTeX:internal-error",
                       "latex_renderer: %s failed for string \"%s\"\n\
* Command:\n\t%s\n\n* Error:\n%s\n\n* Stdout:\n%s",
                       caller.c_str (), txt.c_str (), cmd.c_str (),
                       result.err_msg ().c_str (),
                       result.stdout_output ().c_str ());
  }

  uint8NDArray
  latex_renderer::render (const std::string& txt, int halign)
  {
    // Render if it was not already done
    auto it = latex_cache.find (key (txt, halign));

    if (it != latex_cache.end ())
      return it->second.first;

    uint8NDArray data;

    // First write the base .tex file
    std::string base_file_name = write_tex_file (txt, halign);

    if (base_file_name.empty ())
      return data;

    // Generate DVI file
    std::string tex_file = quote_string (base_file_name + ".tex");
    std::string dvi_file = quote_string (base_file_name + ".dvi");
    std::string log_file = quote_string (base_file_name + ".log");

    process_execution_result result;
    std::string cmd = (m_latex_binary + " -interaction=nonstopmode "
                       + "-output-directory=" + quote_string (m_tmp_dir) + " "
                       + tex_file);

#if defined (OCTAVE_USE_WINDOWS_API)
    cmd = quote_string (cmd);
#endif

    result = run_command_and_return_output (cmd);

    if (result.exit_status () != 0)
      {
        warn_helper ("latex", txt, cmd, result);

        if (txt != "?")
          {
            write_tex_file ("?", halign);

            result = run_command_and_return_output (cmd);
            if (result.exit_status () != 0)
              return data;
          }
        else
          return data;
      }

    double size_factor = m_fontsize / 10.0;


    // Convert DVI to SVG, read file and store its content for later use in
    // gl2ps_print
    std::string svg_file = base_file_name + ".svg";

    cmd = (m_dvisvg_binary + " -n "
           + "-TS" + std::to_string (size_factor) + " "
           + "-v1 -o " + quote_string (svg_file) + " "
           + dvi_file);

#if defined (OCTAVE_USE_WINDOWS_API)
    cmd = quote_string (cmd);
#endif

    result = run_command_and_return_output (cmd);

    if (result.exit_status () != 0)
      {
        warn_helper ("dvisvg", txt, cmd, result);
        return data;
      }

    std::ifstream svg_stream (svg_file);
    std::string svg_string;
    svg_string.assign (std::istreambuf_iterator<char> (svg_stream),
                       std::istreambuf_iterator<char> ());

    // Convert DVI to PNG, read file and format pixel data for later use in
    // OpenGL
    std::string png_file = base_file_name + ".png";

    cmd = (m_dvipng_binary + " " + dvi_file + " "
           + "-q -o " + quote_string (png_file) + " "
           + "-bg Transparent -D "
           + std::to_string (std::floor (72.0 * size_factor)));

#if defined (OCTAVE_USE_WINDOWS_API)
    cmd = quote_string (cmd);
#endif

    result = run_command_and_return_output (cmd);

    if (result.exit_status () != 0)
      {
        warn_helper ("dvipng", txt, cmd, result);
        return data;
      }

    if (! read_image (png_file, data))
      return data;

    // Cache pixel and svg data for this string
    latex_cache[key (txt, halign)] = latex_data (data, svg_string);

    if (m_debug)
      std::cout << "* Caching " << key (txt, halign)
                << " (numel: " << latex_cache.size () << ")\n";

    return data;
  }

  void
  latex_renderer::text_to_pixels (const std::string& txt, uint8NDArray& pixels,
                                  Matrix& bbox, int halign, int valign,
                                  double rotation,
                                  const caseless_str& /*interpreter*/,
                                  bool handle_rotation)
  {
    // Return early for empty strings
    if (txt.empty ())
      return;

    if (ok ())
      pixels = render (txt, halign);
    else
      pixels = uint8NDArray (dim_vector (4, 1, 1), static_cast<uint8_t> (0));

    if (pixels.ndims () < 3 || pixels.isempty ())
      return;  // nothing to render

    // Store unrotated bbox size
    bbox = Matrix (1, 4, 0.0);
    bbox (2) = pixels.dim2 ();
    bbox (3) = pixels.dim3 ();

    // Now rotate pixels if necessary
    int rot_mode = rotation_to_mode (rotation);

    if (! pixels.isempty ())
      rotate_pixels (pixels, rot_mode);

    // Move X0 and Y0 depending on alignments and eventually swap values
    // for text rotated 90° 180° or 270°
    fix_bbox_anchor (bbox, halign, valign, rot_mode, handle_rotation);
  }

  base_text_renderer*
  make_latex_text_renderer (void)
  {
    latex_renderer *renderer = new latex_renderer ();

    return renderer;
  }
}
